A first conventional tool display rack known to applicant is shown in FIG. 5 and includes two holes 10 for hanging the board 11 of the rack on a wall, and a plurality of U-shaped clamping members 12 extending from a side of the board 11. Each clamping member 12 has a retaining space 13 for a tool (not shown) retained therein and a narrow opening 14 communicating with the retaining space 13 so that a shank portion of the tool can be removed from the clamping member 12 via the opening 14. It is obviously that the tool can be easily taken from the rack because that is no locking means to secure the tool to the board 11. A second conventional tool display rack known to applicant is shown in FIG. 6 and includes a hole 10 for hanging the board 11 of the rack on a wall and two apertures 100 for engaging a retainer 16. Two pairs of plates 15 respectively extend from a side of the board 11 and each aperture 100 is located between the two plates 15 corresponding thereto. One of each pair of plates 15 has a protrusion 150 extending laterally inward therefrom. The retainer 16 is an inverted U-shaped member and has a slot 160 defined in each leg of the retainer 16. The two legs will be inserted into the two apertures 100 and the two protrusions 150 are engaged with the two slots 160 in the two legs of the retainer 16. Therefore, a tool can be retained between the board 11 and the retainer 16. Nevertheless, when the rack is bought, the user has to cut the retainer 16 to take the tool and once the retainer 16 is cut, the rack cannot be used anymore.
The present invention intends to provide a tool display rack that can be used to retain a tool after the rack is purchased and the retaining plate is cut.